Memory cell arrays MCA1 . . . MCAm, sense amplifier arrays SAA1 . . . SAAm and a voltage supply circuit 600 are shown in FIG. 7.
A memory cell array MCAi (1.ltoreq.i.ltoreq.m) includes a plurality of memory cells and a plurality of bit line pairs. Each A bit line pair is connected to a memory cell and is provided with a data stored in the memory cell.
A sense amplifier array SAAi includes a plurality of sense amplifier circuits. Each sense amplifier circuit is connected to one of the bit line pairs in the MCAi and amplifies a voltage difference between the bit line pair.
The voltage supply circuit 600 supplies an operational voltage for the sense amplifier circuits in the sense amplifier arrays SAA1 . . . SAAm. The voltage supply circuit 600 is comprised of an operational amplifier circuit 601 and a p-channel type MOS transistor 603. An output terminal of the operational amplifier 601 is connected to a gate electrode of the MOS transistor 603. A source of the MOS transistor 603 is connected to a node which receives a power supply voltage from an outside power supply. A drain of the MOS transistor 603 is connected to conductive lines. Each conductive line is located in one of the sense amplifier arrays and is connected to the sense amplifier circuits for supplying the operational voltage.
A first input terminal of the operational amplifier circuit 601 is connected to a reference voltage Vr which is a substantially constant voltage and a second input terminal is connected to the drain of the MOS transistor 603.
In the semiconductor memory device mentioned above, if a voltage on the drain of the MOS transistor 603 becomes lower than the reference voltage Vr because of a current consumption in the sense amplifier array, the MOS transistor 603 turns on in response to a control signal which is provided from the output terminal of the operational amplifier 601. Then, the voltage on the drain is raised.
On the contrary, if a voltage on the drain of the MOS transistor 603 becomes higher than the reference voltage Vr, the MOS transistor 603 turns off in response to the control signal. Then, the voltage on the drain gradually falls because of the current consumption in the sense amplifier array. If the voltage becomes lower than the reference voltage Vr, the operation mentioned above is repeated.
Therefore, the voltage on the drain of the MOS transistor 603, that is the voltage on the conductive lines which supply the operational voltage to the sense amplifier circuits, is regularly maintained.
However, as the drain of the MOS transistor 603 is connected to a large number of sense amplifier arrays (the conductive lines), an undesirable delay can occur between sense amplifier arrays which are located in the vicinity of the drain and sense amplifier arrays which are located distant from the drain. This delay is caused by parasitic resisters, parasitic capacitors and the current consumption in the sense amplifier arrays.
This delay is undesirable in that it adversely influences a high speed operation in the semiconductor memory device. Particularly, in a dynamic random access memory which requires the highest speed, such delays may be a serious problem.